Dual mode air purifier and method

ABSTRACT

A dual mode compressed air purifier is presented having a cart for transportation purposes and including a chemical medium purifier with a regenerable filter cartridge. A first purification mode removes water, carbon dioxide, hydrocarbons and other impurities from compressed air which is then available for supplied air respirators of workers in hazardous environments. In the second or regeneration mode compressed air is heated and then delivered to the chemical medium purifier whereby impurities removed by the medium during purification are collected and expelled by the hot air and are then exhausted from the dual mode air purifier. The cooling cycle of the regeneration mode returns the chemical medium purifier to an ambient temperature after which purifying can begin again.

This is a continuation of application Ser. No. 098,978, filed Sept. 21,1987, now U.S. Pat. No. 4,790,860.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transportable air purifier forremoving pollutants from compressed air for supplied air respirators andotherwise for use in industrial applications.

2. Description of the Prior Art and Objectives of the Invention

Employee safety has become increasingly important in manufacturing andprocessing operations in recent years with the enactment of new stateand federal laws. Particular attention has been directed to the airbreathed by employees during maintenance, handling and removal ofhazardous materials such as various solvents or asbestos which hasminute particles that are harmful when airborne. In order to protectemployees from such hazardous particulate and gaseous matter, suppliedair respirators are furnished to workers which are conventionallyconnected to a stationary central source for purified air. Suchconventional purifier sources may have a disposable cartridge which mustbe periodically changed and replaced. Other purifiers of the permanenttype usually provide for a regeneration cycle and usually have twofilter cylinders or chambers whereby when one cylinder is beingregenerated the other cylinder is simultaneously used to purify therequired air. As different employees often on different shiftscontinually use such purifying systems, the purifiers frequently are notproperly attended and the filters therein become saturated withpollutants and lose their filtration and absorption qualities, thusallowing harmful pollutants to pass through to the respirators worn bythe workers. While some of the prior art purifying devices includemonitors with signals to identify expended filters, such purifyingdevices are oftentimes inconvenient to maintain and expensive to serviceand are therefore neglected, creating a health hazard for the workers.

With the aforesaid problems and disadvantages associated withconventional air purifying devices, the present invention was conceivedand one of its objectives is to provide a dual mode air purifier andmethod for purifying compressed air having purification and regenerationmodes which is convenient and simple to operate.

It is also an objective of the invention to provide a compressed airpurifier in which the regeneration mode has both heating and coolingcycles.

Yet another objective is to provide a purifying device which has a cartwhich allows the purifier to be easily and conveniently moved by asingle worker during use as needed and after use to another location ifdesired for regeneration purposes.

It is still another objective of the present invention to provide a dualmode air purifier which includes an air filter having a heater attachedthereto for providing hot purge air directly to the air filter mediumduring the regeneration cycle to quickly and efficiently regenerate thefilter medium.

Another objective of the present invention is to provide an economicalair purifier and method which has the capacity for continued use duringa typical work shift and which can thereafter be moved by a singleemployee to another location for regeneration during off-hours.

Also, another objective of the present invention is to provide a dualmode air purifier and method which can be correctly operated byrelatively unskilled employees after only minimal training.

Other objectives and advantages of the present invention will becomeapparent to those skilled in the art as a more detailed description ofthe invention is presented below.

SUMMARY OF THE INVENTION

The aforesaid and other objectives are realized by a dual mode airpurifier having a chemical medium purifier consisting of filter housingcontaining a regeneratable filter medium cartridge. The first orpurification mode is determined by a selector switch and can be changedto the regeneration mode having "heating" and "cooling" cycles simply byturning a selector switch. Attached to the filter housing is an airheater featuring a heating element which allows hot air produced by theheating element to be passed directly to the filter medium within thefilter cartridge. The chemical medium purifier and air heating deviceare supported within a movable cart for transportation as requiredduring use or thereafter for movement to another location forregeneration. The method of operating the dual mode purifier is simplyto make the proper line connections to an air compressor and to thesupplied air respirators and with the selector switch set to "purify",the purifier is operational. Compressed air will enter the air filtermedium for contaminant removal and thereafter passes out of the filterto the air respirators worn by workmen.

Purging or regenerating the chemical medium purifier is accomplished byconnecting the air heater to a suitable electrical source such as 220 vAC and setting the selector switch to "heat". Compressed air is directedinto the heater where its temperature is raised and the hot air is thenpassed to the chemical medium purifier where the heated air desorbscontaminants contained in the filter medium which is thereafterexhausted. Next, by manually turning the selector switch after aprescribed time to "cool", the cooling cycle allows ambient compressedair to be directed through the deenergized heater and around the outsideof the filter cartridge after which the air is then exhausted andpurifying can begin again.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 demonstrates a side elevational view of a cart cabinet housingthe dual mode air purifier;

FIG. 2 is a front elevational view of the cart cabinet as shown in FIG.1;

FIG. 3 illustrates an enlarged cross-sectional view of the invertedsubstantialy J-shaped filter assembly including chemical medium purifierand heating components removed from the cabinet;

FIG. 4 demonstrates in schematic fashion the flow of compressed air inthe purification mode;

FIG. 4A shows an enlarged schematic flow through the filter assembly ofFIG. 4 in the purification mode;

FIG. 5 demonstrates in schematic fashion the flow of compressed air inthe heating cycle of the regeneration mode;

FIG. 5A shows an enlarged schematic flow through the filter assembly inFIG. 5 in the heating cycle;

FIG. 6 demonstrates in schematic fashion the flow of compressed air inthe cooling cycle of the regeneration mode;

FIG. 6A shows an enlarged schematic flow through the filter assembly ofFIG. 6 in the cooling cycle;

FIG. 7 depicts a typical simplified set-up in schematic form utilizingthe dual mode purifier; and

FIG. 8 illustrates an electrical schematic of certain of the components.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A schematic view of the preferred form of the components of the dualmode air purifier is shown in FIG. 4 having a chemical medium purifierwith a regeneratable filter cartridge contained within a filter housingas seen in FIG. 3. The cartridge includes three (3) compartments, eachcompartment containing a different chemical medium for compressed airpurification. Attached to the chemical medium purifier is an air heaterof the electrical resistance type for supplying hot air duringregeneration of the filter medium.

The preferred method of the invention comprises purifying compressed airby directing air from the compressor to the compressed air inlet of thedual mode air purifier and supplied air respirators are connected to thepurified air outlet. Two internal solenoid air valves are electricallyoperated and in the purifying mode are deenergized. Regeneration of thespent chemical medium consists of connecting the unit to a suitableelectrical source which will energize a directional control valveterminating the purification mode. A selector switch set to "H" (heat)on the control panel will change the inlet directional control valve todirect compressed air at a lower pressure into an air heater where it isheated to approximately 450° F. and thereafter passed into the chemicalmedium purifier where contaminants are removed from the filter mediumand the air is then exhausted. Lastly, unheated air is directed aroundthe outside of the chemical filter cartridge for cooling purposes bymanually changing the selector switch to "C" (cool) which changes theinlet directional control valve thereby allowing ambient air tocirculate around the outside of the filter medium after which it too isthen exhausted.

DETAILED DESCRIPTION OF THE DRAWINGS AND OPERATION OF THE INVENTION

Dual mode air purifier 10 is shown in schematic view in FIGS. 4, 5 and 6in which the components are contained within cart housing 35 of movablecart 22 as seen in FIG. 1. Cart housing 35 is permanently attached tocart frame 36 whereby dual mode air purifier 10 can be rolled on wheels37 and positioned at a specific location within a factory or otherwiseas required for supplying purified compressed air and can be easilyrolled or moved to a second location for regeneration purposes. Inaddition to inverted substantially J-shaped filter assembly means 18comprising chemical medium purifier 11 and air heating means 12 as shownin FIG. 3, cart housing 35 contains other components as seen in theschematic views. In the purification mode or "P" setting on switch 39,raw compressed air from a conventional industrial air compressor 65(FIG. 7) is the supply source. Compressed air inlet 50 (FIG. 4) isjoined to a conventional air compressor supply line 66 (FIG. 7) whichpasses air through supply conduit 56 (FIG. 4). Pressure relief valve 41senses the incoming air pressure and acts as a safety valve by ventingair having a pressure over a preset maximum. Inlet pressure gauge 42provides the operator with the proper pressure reading and is positionedas shown in FIG. 2 on the front of cart housing 35. Mechanical separator43 with automatic drain and oil removal filter 44 also having anautomatic drain is provided as is differential pressure switch 48 whichprevents the pressure therebetween from increasing above a maximumestablished level without issuing a warning signal. Air passing alongsupply conduit 56 next encounters (1) two-way on/off solenoid controlvalve 40 which is deenergized and in the "on" state is in thepurification mode, and (2) pressure relief valve 46 set to 5 psi. Airwill flow through solenoid control valve 40 and not through pressurerelief valve 46 in the purification mode because pressure is greater inline 45 than in line 61. As seen in FIG. 4 control valve 40 is in theopen position (deenergized) thereby allowing compressed air flowingtherethrough to enter filter housing air inlet line 19 and to pass intothe chemical medium purifier 11 as better seen in FIG. 4A. The pressurein line 45 is greater than in line 61 thus preventing air flow from line61 through check valve 47 to line 45. This pressure differentialprevents bypass of the compressed air around chemical medium cartridge14. Control valve 20 is a solenoid operated three-way control valve witha center position, all ports blocked mode, and is not energized in thepurification mode. Thus, compressed air will not pass through controlvalve 20 in its deenergized state. Chemical medium purifier 11 whichincludes medium catridge 14 has three (3) compartments of chemicalfilter medium therein. As seen in FIG. 3 top medium compartment 23contains activated carbon 26, middle medium compartment 24 contains amanganese dioxide catalyst 27 and bottom medium compartment 25 containsan alkali-metal alumino silicate 28 commonly referred to as a molecularsieve. Medium cartridge 14 is contained within filter housing 13 ofchemical medium purifier 11 and is affixed therein. Coil springs 33insures the chemicals within medium cartridge 14 are tightly compactedpreventing them from becoming airborne. Top cap 38 of medium cartridge14 includes a series of apertures 58 whereby air entering air inlet line19 in the purification mode passes into medium cartridge 14 throughbottom apertures 59 for exiting through apertures 58 where the purifiedair then moves through filter housing air outlet line 17. The purifiedair then passes through particle filter 52 (FIG. 4), moisture indicator53, minimum pressure valve 54 which is set to maintain 50 psi, andthrough distribution outlet 55 where it is then delivered to one or morebreathing apparatus such as supplied air respirators 70 worn by workmenas seen in FIG. 7. Minimum pressure valve 54 serves two purposes. Firstit insures that air passing through air filter means 18 maintains aminimum pressure to insure a minimum desired water vapor condensationrate and secondly, it maintains a minimum pressure on line 45 asexplained earlier above.

During the heating cycle of the regeneration mode with a 110 v AC supplyconnected, compressed air enters air inlet 50 as above described andproceeds first to directional solenoid control valve 40 which is closedas seen in FIG. 5 and said compressed air is then directed into heatingmeans air inlet line 31. Control valve 40 is energized in this cycle asis control valve 20 and manual selector switch 39 on the front panel ofmovable cart 22 is set to "H" (heat") which is in electricalcommunication with valves 20 and 40. Thus when first control valve 40 isclosed and second control valve 20 is operating in the heating cycle,the air flow is as depicted in FIGS. 5 and 5A. After passing throughheating means air inlet line 31 the compressed air then passes into theadjustable pressure regulator 46 which is preset to reduce pressure to 5psi or to a pressure to maintain a 5 scfm flow rate. Air is directedthrough line 61 to check valve 47 which allows air to pass onlyforwardly as described. The compressed air then enters air heating means12 (via line 45) enclosed in air heating means housing 21 (FIG. 3) whereit encounters heating element 15 which comprises an electricalresistance strip heater with heating element fins 30. The temperature ofthe air is increased in heating element 15 to approximately 450° to 500°F. where it is forced upwardly a short distance through filter housingtop opening 16 and into medium cartridge 14 (FIG. 3). The hot air flowsinto chemical medium 26, 27 and 28 (FIG. 3) where it will dry (collect)any moisture contained therein. The flow into cartridge 14 will alsoexpel pollutants and contaminants to refresh said chemical mediumcontained therein. Thereafter the air containing pollutants exitsconduit 19 through second control valve 20 and exhaust muffler 51 (FIG.5). Once the regeneration heating cycle has proceeded for a calculatedtime to remove the pollutants and moisture from medium cartridge 14contained within chemical medium purifier 11, such as with a purge rateof approximately 5 scfm, heating is then stopped and the cooling cyclecan begin.

Selector switch 39 is now manually set to "C" (cool). In this cycle,heating element 15 is not energized and air flows around the outside ofmedium cartridge 14 allowing it and its contents to approach ambienttemperature (see FIG. 6A). Medium cartridge 14 is cooled by having theunheated ambient air flow along a path on the outside of cartridge 14and then through second control valve 20 to exhaust muffler 51. FIGS. 6and 6A illustrate this flow path.

As would be understood, the present invention makes it extremelyconvenient to purify compressed air at various sites within a plantwhere compressed air is available and at night or during off shifts, thedual mode purifier can be rolled to another location and regenerated foruse the next day. As an added precaution, alarm device 62 with switch 60(FIG. 8) as shown in FIGS. 4, 5, and 6 indicates through alarm device 62the presence of carbon monoxide; moisture indicator 53 will detect thepresence of excess water; and differential pressure switch 48 will soundalarm 64 or light a lamp indicating that mechanical separator 43 withautomatic drain and/or the oil removal filter 44 with automatic drain isclogged.

The illustrations and examples provided herein are for explanatorypurposes and are not intended to limit the scope of the appended claims.

I claim:
 1. A method of operating an air purifier having a chemicalmedium cartridge within a filter housing with the medium cartridgespaced inwardly from the walls of the filter housing to form apassageway between the medium cartridge and the housing comprising thesteps of:(a) purifying air by directing air into the filter housing andthrough the chemical medium cartridge for contaminant removal, (b)regenerating the chemical medium within the cartridge by:(1) directingheated air into the chemical medium to remove contaminants therefrom,(2) exhausting the heated air from the chemical medium; and (3) coolingthe chemical medium by directing ambient air through the passagewayaround the outside of the medium cartridge.
 2. The method of claim 1wherein the step of regenerating the chemicals medium comprisesdirecting heated air from an electrical heating means to the chemicalmedium.
 3. The method of claim 1 wherein the step of cooling thechemical medium includes exhausting the air from the passageway aroundthe outside of the medium cartridge.
 4. The method of claim 1 andincluding the step of utilizing a selector switch to change the airpurifier from purification to regeneration mode.
 5. The method of claim4 wherein the step of utilizing a selector switch comprises changing theselector switch manually.
 6. The method of claim 1 wherein the step ofpurifying air by directing air into the filter housing comprisesdirecting air in a first direction into the chemical medium andthereafter directing heated air into the chemical medium in a seconddirection.
 7. The method of claim 1 wherein the step of purifying aircomprises directing air into the filter housing in a first direction,the step of regenerating the chemical medium comprises directing airinto said housing in a second direction, and the step of cooling thechemical medium comprises directing air into the filter housing andaround the chemical medium in the second direction.
 8. An air purifierhaving a purification and a regeneration mode comprising: a chemicalmedium purifier, said medium purifier having:(a ) a filter housing, and(b) a medium cartridge, said medium cartridge contained within andspaced inwardly from said filter housing to form a passageway betweensaid filter housing and said medium cartridge, said medium cartridge forremoving pollutants passing therethrough in the purification mode, airheating means, said heating means having: (c) heating means housing, and(d) a heating element, said heating means housing containing saidheating element, said filter housing communicating with said heatingmeans housing whereby, in the regeneration mode hot air can pass fromsaid heating means into said filter medium cartridge and thereafterambient air can pass from said heating means housing to said filterhousing and around the outside of said medium cartridge in saidpassageway.
 9. An air purifier as claimed in claim 8 and including aselector switch, said selector switch connected to said filter housingfor controlling the operational mode.
 10. An air purifier as claimed inclaim 9 wherein said selector switch, when turned to a first settingcauses air to travel in a first direction through said medium purifierand when turned to a second setting causes air to travel through saidmedium purifier in a second direction.
 11. An air purifier as claimed inclaim 8 wherein said filter housing and said heating means housing arecontained within a movable cart.
 12. An air purifier as claimed in claim8 wherein said medium cartridge comprises a plurality of mediumcompartments.